Millimeter wave antenna array

ABSTRACT

An antenna array may include a plurality of printed circuit boards (PCBs) oriented in a stacked arrangement, parallel to and spaced apart from one another. Each of the PCBs may include a linear array of antenna elements, which cooperate with the linear arrays of antenna elements on other PCBs to form a two-dimensional array of antenna elements. The PCBs may be supported at one end by a common backplate in a cantilevered manner, with the linear arrays of antenna elements located near the free end of the PCBs. The PCBs may include a thicker portion and a thinner portion, and the thinner portion may include a heat sink or other thermal dissipation structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

This application claims the benefit of U.S. Provisional Application No.62/862,516, filed Jun. 17, 2019, and entitled MILLIMETER WAVE ANTENNAARRAY, the disclosure of which i.e. hereby incorporated by reference inits entirety.

BACKGROUND Field of the Disclosure

Embodiments described herein relate to antenna arrays, and in particularto two-dimensional antenna arrays which can be used in conjunction withbeamforming circuitry.

Description of the Related Art

In some embodiments, a two-dimensional array of antenna elements can beformed on a single substrate. However, the controlling circuitry used inconjunction with such an antenna array may have a footprint considerablylarger than the antenna array itself. This can be of particular concernwhere the antenna array is configured for operation at shorterwavelengths, such as in the millimeter wave band.

In some embodiments, the controlling circuitry can be supported by oneor more additional substrates distinct from the antenna array substrateitself. In some particular embodiments, the antenna array substrate maybe positioned at an angle to a plurality of printed circuit boards(PCBs) supporting circuitry for controlling the array of antennaelement. However, a suitable interface between the PCBs and thenon-coplanar substrate supporting the antenna elements can be complex,presenting difficulties with respect to both design and manufacture.

SUMMARY

In one broad aspect, an antenna array is provided, including abackplane, and a plurality of printed circuit boards supported at afirst edge by the backplane, the plurality of printed circuit boardsarranged parallel to and spaced apart from one another, each of theplurality of printed circuit boards including a linear array of dipoleantenna elements arranged along a second free edge of the printedcircuit board opposite the first edge of the printed circuit board, thelinear arrays of dipole antenna elements on each of the plurality ofprinted circuit boards cooperating with one another to form atwo-dimensional array of printed circuit boards.

In some embodiments, the printed circuit boards can be orthogonal to thebackplate. In some embodiments, each of the plurality of printed circuitboards can support a beamforming integrated circuit operably connectedto at least a portion of the linear array of dipole antenna elements. Insome embodiments, each of the plurality of printed circuit boards cansupport a second beamforming integrated circuit operably connected to atleast a portion of the linear array of dipole antenna elements. In someembodiments, each of the plurality of printed circuit boards can supporta plurality of switches, each of the plurality of switches arrangedbetween the beamforming integrated circuit and a dipole antenna elementof the linear array of dipole antenna elements.

In some embodiments, each of the plurality of printed circuit boards caninclude a first portion proximate the backplane and having a firstthickness and a second portion proximate the second edge of the printedcircuit board and having a second thickness greater than the firstthickness. In some embodiments, each of the plurality of printed circuitboards can include a thermal dissipation structure supported by thefirst portion of the printed circuit board. In some embodiments, thethermal dissipation structure can include a plurality of fins.

In some embodiments, the linear array of dipole antenna elements can beat least partially embedded within the second portion of the printedcircuit board. In some embodiments, the linear array of dipole antennaelements can include a first subset of dipole antenna elements orientedin a first direction and a second subset of dipole antenna elementsoriented in a second direction. In some embodiments, the first subset ofdipole antenna elements can be horizontally oriented and include a pairof parallel, non-coplanar sections, and the second subset of dipoleantenna elements can be vertically oriented and include a pair ofaxially aligned vias spaced apart from one another. In some embodiments,the dipole antenna elements of the first subset of dipole antennaelements can alternate with the dipole antenna elements of the secondsubset of dipole antenna elements along the length of the linear arrayof dipole antenna elements.

In some embodiments, each of the plurality of printed circuit boards canalso include a ground plane oriented substantially parallel to a majorsurface of the printed circuit board, and a plurality of conductive viasoriented orthogonally to the ground plane and connected to the groundplane. In some embodiments, the plurality of conductive vias can bearranged in a pattern extending generally parallel to the second edge ofthe circuit board, and the linear array of dipole elements can belocated between the plurality of conductive vias and the second edge ofthe printed circuit board.

In another broad aspect, a printed circuit is provided, the printedcircuit board configured to cooperate with a plurality of printedcircuit boards to form a two-dimensional array of antenna elements, theprinted circuit board including a first section proximate a first edgeof the printed circuit board, the printed circuit board configured to besupported at first edge of the printed circuit board by a backplane, thefirst section having a first thickness, a second section proximate asecond edge of the printed circuit board, the second edge of the printedcircuit board having a second thickness greater than the firstthickness, a linear array of dipole antenna elements embedded at leastpartially within the second section of the printed circuit boardadjacent the second edge of the printed circuit board, beamformingcircuitry supported by the printed circuit board and in electricalcommunication with the linear array of dipole antenna elements, and athermal dissipation structure supported by the first section of theprinted circuit board.

In some embodiments, the linear array of dipole antenna elements caninclude a plurality of horizontally-oriented dipole antenna elementsalternating with a plurality of vertically-oriented dipole antennaelements. In some embodiments, the plurality of vertically-orienteddipole antenna elements can include a plurality of vertically-extendingdipole vias, and the printed circuit board can also include a pluralityof vertically-extending ground vias, where the vertically-extendingdipole vias can be located closer to the second edge of the printedcircuit board than the vertically-extending ground vias.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present disclosure will becomemore fully apparent from the following description and appended claims,taken in conjunction with the accompanying drawings. Understanding thatthese drawings depict only several embodiments in accordance with thedisclosure and are not to be considered limiting of its scope, thedisclosure will be described with additional specificity and detailthrough use of the accompanying drawings. In the following detaileddescription, reference is made to the accompanying drawings, which forma part hereof. In the drawings, similar symbols typically identifysimilar components, unless context dictates otherwise.

FIG. 1 is a perspective view schematically illustrating atwo-dimensional array of antenna elements comprising antenna elements atthe free ends of each of a plurality of cantilevered printed circuitboards (PCBs).

FIG. 2 is a top plan view of PCB section illustrating an exemplarydipole antenna element design.

FIG. 3 is a perspective view schematically illustrating an exemplary8×16 array of dipole antenna elements formed near the free edges ofeight distinct PCBs.

FIG. 4 is a perspective view schematically illustrating an exemplary 3×3array of dipole elements formed near the free edges of three distinctPCBs.

FIG. 5 is a plot illustrating elevation scanning of an exemplary antennaarray.

FIG. 6A is a top plan view schematically illustrating an antenna arraysuch as the array of FIG. 4. FIG. 6B is a plot illustrating azimuthscanning of the antenna array of FIG. 6A using a uniform distribution.

FIG. 7A is a top plan view schematically illustrating an antenna arraysuch as the array of FIG. 4. FIG. 7B is a plot illustrating azimuthscanning of the antenna array of FIG. 7A using a Taylor distribution.

FIG. 8 is a plot of return loss of the center dipole of a 3×3 array suchas the array of FIG. 4.

FIG. 9A is a perspective view illustrating a simulation model andcoordinate system for a 3×3 array such as the array of FIG. 4. FIG. 9Bis a perspective view illustrating the far field radiation pattern of asingle element of the array at 38.8 GHz.

FIG. 10A is a plot of a Y-Z planar cut of the far field radiationpattern of the center dipole of a 3×3 array such as the array of FIG. 9Aat 38.8 GHz. FIG. 10B is a plot of an X-Z planar cut of the far fieldradiation pattern of the center dipole of the 3×3 array at 38.8 GHz.

FIGS. 11A and 11B are Y-Z planar cuts of the far field radiation patternof the center dipole of a 16×16 array such as the array of FIG. 1 at38.8 GHz.

FIG. 12 is a perspective view of one embodiment of a PCB which can beused in a dual polarized array including a plurality of alternatelypolarized elements.

FIG. 13 is a perspective view illustrating a dual polarized antennaarray formed by a plurality of PCBs, with alternating horizontallyoriented dipole elements and vertically oriented dipole elements.

FIGS. 14A and 14B illustrate Y-Z and X-Z planar cuts of the radiationpatterns of the horizontally polarized antenna elements of an antennaarray such as that of FIG. 13.

FIGS. 15A and 15B illustrate Y-Z and X-Z planar cuts of the radiationpatterns of the vertically polarized antenna elements of an antennaarray such as that of FIG. 13.

FIG. 16A is a partial cutaway perspective view of an alternativeembodiment of a PCB which can form a part of a dual-polarized antennaarray. FIG. 16B is a detail partial cutaway perspective view of the PCBof FIG. 16A. FIG. 16C is another detail partial cutaway perspective viewof the PCB of FIG. 16A, showing embedded striplines within the PCBstructure. FIG. 16D is a side perspective view of the PCB of FIG. 16A.

FIG. 17 is a perspective view illustrating another embodiment of a PCBhaving a plurality of components supported on a first side thereof.

FIG. 18 is a top plan view schematically illustrating an alternativeembodiment of a via arrangement in which a portion of the signal linesare not coplanar with the printed dipole components of the embeddeddipole antenna elements.

FIG. 19 is a cross-sectional view schematically illustrating anembodiment of a layer stack which can be used to fabricate a PCB such asthe PCB of FIG. 17.

FIG. 20A is a top plan view of a PCB such as the PCB of FIG. 17,illustrating certain vias and conductive traces formed between variouscomponents. FIG. 20B is a bottom plan view of the PCB of FIG. 20A.

While the above-identified drawings set forth presently disclosedembodiments, other embodiments are also contemplated, as noted in thediscussion. This disclosure presents illustrative embodiments by way ofrepresentation and not limitation. Numerous other modifications andembodiments can be devised by those skilled in the art which fall withinthe scope and spirit of the principles of the presently disclosedembodiments.

DETAILED DESCRIPTION

In some embodiments, a two-dimensional antenna array can be formedacross a plurality of discrete printed circuit boards (PCBs) or othersupporting substrate, with each of the plurality of PCBs having a lineararray of antenna elements formed thereon. When the PCBs are arrangedrelative to one another, the linear arrays of antenna elements formed oneach of the PCBs can cooperate to form the two-dimensional antennaarray.

In providing a multi-dimensional array of antenna elements spread acrossa plurality of distinct PCBs, each PCB can support controllingcircuitry, such as beamforming circuitry, which can control theoperation of those antenna elements on the same PCB. Such an arrangementcan provide multiple substrates for supporting controlling circuitry andother components of the antenna array, while avoiding the need to designand fabricate a complex interface between a common antenna arraysubstrate and a plurality of additional substrates. This arrangement canalso be beneficial with respect to thermal management of the antennaarray and controlling circuitry.

While the structures described herein can be adapted for use with a widerange of operational frequencies, the structures may be particularlysuited for use with frequencies in or near the millimeter wave range. Insome embodiments, the operational frequency of the antenna array may bebetween 20 GHz and 39 GHz. In some particular embodiments, theoperational frequency of the antenna array may be between 24 and 30 GHz.In some exemplary embodiments, the antenna arrays can be used withfrequencies at or around 28 GHz, or at or around 39 GHz. Otherfrequencies higher and lower than these ranges may also be used.

FIG. 1 is a perspective view schematically illustrating atwo-dimensional array of antenna elements comprising antenna elements atthe free ends of each of a plurality of cantilevered printed circuitboards (PCBs).

FIG. 1 illustrates an antenna array 100 including a plurality of printedcircuit boards (PCBs) 110. The plurality of PCBs 110 are arrangedgenerally parallel to one another, and are supported at one end 112 by abackplane 102. The opposite ends 114 of the PCBs 110 are free ends, suchthat the PCBs 110 are supported in a cantilevered arrangement by thebackplane 102.

A linear array of antenna elements 120 are formed along each of the freeends 114 of the PCBs 110, opposite the backplane 102. The linear arraysof antenna elements 120 along each of the free ends 114 of the PCBs 110cooperate with one another to form a two-dimensional array of antennaelements 120, in which each row of the antenna elements 120 is locatedon a different PCB 110.

FIG. 2 is a top plan view of PCB section illustrating an exemplarydipole antenna element design. Dipole antenna 120 may include a firstdipole arm 130 including a proximal section 132 extending normal to thebackplane and a distal section 134 extending perpendicularly from theproximal section 132 in a first direction parallel to the backplane.Dipole antenna 120 also includes a second arm 140 including a proximalsection 142 extending normal to the backplane and a distal section 144extending perpendicularly from the proximal section 142 in a seconddirection opposite the first direction in which the distal section 134of the first dipole arm 140 extends.

The proximal sections 132 and 142 of the first and second dipole arms130 and 140 may comprise parallel, overlapping striplines, and thedistal sections 134 and 144 may be parallel striplines which extend inopposite directions, and do not have substantial overlap.

In the illustrated embodiment, the PCB also includes a director 150which includes a strip located outward of the dipole arms 130 and 140,closer to the free end 114 of the PCB 110. The edges of the dipole arms130 and 140 may extend farther outward than the edges of the director150. The director 150 may be coplanar with one of the dipole arms 130 or140.

In the illustrated arrangement, the two dipole arms 130 and 140 arelocated within parallel respective planes, and the two dipole arms 130and 140 may be separated by at least one sublayer of the PCB 110.Because all of the dipole arms 130 are coplanar with one another, andall of the dipole arms 140 are also coplanar with one another, thedistal portion of the PCB 110 in which the dipole antenna elements 120are defined may be comparatively thin, and the proximal portion of thePCB 110 may be comparatively thicker to provide additional structures.In some embodiments, a proximal section of at least one of the dipolearms may be in contact with a ground plane within or on a surface of thePCB 110 in the thicker proximal portion of the PCB 110.

In some embodiments, the dipole arms 130 and 140 may be etched orotherwise formed on exposed opposite sides of a PCB sublayer. In otherembodiments, as discussed in greater detail below, the dipole arms 130and 140 may be embedded within the PCB, with surrounding sublayers onone or both sides of the PCB, and the distal portion of the PCB may bethicker to accommodate the additional sublayers and other components.

As discussed in greater detail below, the PCBs 110 may supportbeamforming circuitry (not shown in FIGS. 1 and 2), which can be used tocontrol the operation of the antenna elements on that PCB 110. Thebeamforming circuitry may comprise integrated circuits (ICs), alsoreferred to as radio frequency integrated circuits (RFICs). Thebeamforming circuitry may be used to steer the antenna.

Because each PCB can support beamforming circuitry and other componentsused to control the antenna elements on that PCB, the multilayer PCBarrangement provides an amount of available surface area which can besubstantially larger than the dimensions of the antenna array itself,while occupying a comparatively small volume.

FIG. 3 is a perspective view schematically illustrating an 8×16 array300 of dipole elements, which can also be used in the generation ofsimulation results, as discussed in greater detail below. FIG. 4 is aperspective view schematically illustrating an exemplary 3×3 array 400of dipole elements. This 3×3 array may be used to model antennabehavior, such as the effects of neighboring dipoles, and may representa subset of a larger array.

The scan loss of a given antenna array will control the usable angularscan range of the array. The scan loss may be a function, in part, ofthe array geometry, including the number of elements and the spacingbetween those elements. The scan loss may also be a function of theelement type used to populate the array. However, the array geometryaffects scan loss independent of the particular antenna array elementtype used.

FIG. 5 is a plot illustrating elevation scanning of an antenna arraygeometry as a function of scan angle theta, where the elements arespaced 0.72 wavelengths apart (7.2 mm) along the elevation axis, with nograting lobe at 30.0 GHz. A 27 dB Taylor distribution was used in thegeneration of this plot. In an embodiment in which the scan requirementfor an antenna array in elevation is lower than the scan requirement inazimuth, larger element spacing along the elevation axis may be used.

FIG. 6B is a plot illustrating azimuth scanning of an antenna arraygeometry as a function of scan angle theta, where the elements arespaced 0.5 wavelengths apart (5.14 mm) along the azimuth axis, with nograting lobe at 30.0 GHz. A uniform distribution was used in thegeneration of this plot. FIG. 6A illustrates the plane 604 along whichthe cuts of FIG. 6B are made, shown relative to the 8×16 antenna array600 such as the array 300 of FIG. 3.

FIG. 7B is another plot illustrating azimuth scanning of an antennaarray geometry as a function of scan angle theta, where the elements arespaced 0.5 wavelengths apart (5.14 mm) along the azimuth axis, with nograting lobe at 30.0 GHz. A 27 dB Taylor distribution was used in thegeneration of this plot. FIG. 7A illustrates the plane 704 along whichthe cuts of FIG. 7B are made, shown relative to the 8×16 antenna array700 such as the array 300 of FIG. 3.

FIG. 8 is a plot of return loss of the center dipole of a 3×3 array suchas the array 400 of FIG. 4. The solid line 806 represents the returnloss of the center dipole, and the dashed lines represent the isolationbetween the center dipole and each of the surrounding 8 dipoles.

FIG. 9A is a perspective view illustrating a simulation model andcoordinate system for a 3×3 array 900 such as the array 300 of FIG. 3.FIG. 9B is a perspective view illustrating the far field radiationpattern 960 of a single element of the array 900 at 38.8 GHz.

FIG. 10A is a plot of a Y-Z planar cut of the far field radiationpattern of the center dipole of a 3×3 array such as array 900 at 38.8GHz. The 3 dB beamwidth is 116 degrees, and the 10 dB beamwidth is 153degrees. FIG. 10B is a plot of an X-Z planar cut of the far fieldradiation pattern of the center dipole of the 3×3 array at 38.8 GHz.

FIGS. 11A and 11B are Y-Z planar cuts of the far field radiation patternof the center dipole of a 16×16 array such as array 100 at 38.8 GHz. InFIG. 11A, the radiation pattern is steered towards an angle of 19.5degrees along the Y-Z axis, with a peak gain of 28.9 dB. The first sidelobe level is 12.7 dB, and the 3 dB beamwidth is 6.7 degrees. In FIG.11B, the radiation pattern is steered towards an angle of 41 degreesalong the Y-Z axis, with a peak gain of 27.4 dB. The first side lobelevel is 11.1 dB, and the 3 dB beamwidth is 8.2 degrees.

In some embodiments, dual polarization may be required. In suchembodiments, an antenna array of alternately polarized elements can beused. FIG. 12 is a perspective view of one embodiment of a PCB which canbe used in such an array. As can be seen in FIG. 12, a distal portion1260 at the free end 1214 of the PCB 1210 can be thicker than a proximalportion 1270 closer to the end at which the PCB 1210 will be supportedby a backplane. The additional thickness can accommodate the inclusionof vertically oriented dipole antennas 1270 with sections orientedorthogonal to the major surfaces of the PCB 1210, in addition tohorizontally oriented dipole antennas oriented parallel to the majorsurfaces of the PCB 1210 and which may be embedded within the thickdistal portion 1260 of the PCB.

Such a design can provide a combination of vertically polarized dipoleantennas and horizontally polarized dipole antennas. In addition,because the PCB design includes both vertically oriented andhorizontally oriented dipole antennas, the PCB 1210 may include aplurality of vertically extending vias 1208 which may cooperate tofunction as a ground plane structure extending generally orthogonal tothe major surfaces of the PCB 1210. These vertically extending vias mayconnect to some or all of the planar ground planes within or on the PCB.

A particular embodiment of a dual polarized antenna array is shown inFIG. 13. The antenna array 1300 of FIG. 13 includes a plurality of PCBs1310. Each of these PCBs 1310 include alternating horizontally orienteddipole antennas 1320 and vertically oriented dipole antennas 1370 alongtheir free ends 1314.

FIGS. 14A and 14B illustrate Y-Z and X-Z planar cuts of the radiationpatterns of the horizontally polarized antenna elements of an antennaarray such as antenna array 1300. The Y-Z planar cut of FIG. 14A has apeak gain of 23.3 db, a first side lobe level of 13.1 dB, and a 3 dBbeamwidth of 12.4 degrees. The X-Z planar cut of FIG. 14B has a peakgain of 23.3 dB, a first side lobe level of 14 dB, and a 3 dB beamwidthof 12.3 degrees.

FIGS. 15A and 15B illustrate Y-Z and X-Z planar cuts of the radiationpatterns of the vertically polarized antenna elements of an antenna suchas antenna 1300. The Y-Z planar cut of FIG. 15A has a peak gain of 23.3db, a first side lobe level of 13.4 dB, and a 3 dB beamwidth of 12.4degrees. The X-Z planar cut of FIG. 15B has a peak gain of 23.3 dB, afirst side lobe level of 13 dB, and a 3 dB beamwidth of 12.2 degrees.

FIG. 16A is a partial cutaway view of an embodiment of a PCB 1610 whichcan form a part of a dual-polarized antenna array. FIG. 16B is a detailpartial cutaway perspective view of the PCB of FIG. 16A. FIG. 16C isanother detail partial cutaway perspective view of the PCB of FIG. 16A,showing embedded striplines within the PCB structure. FIG. 16D is a sideperspective view of the PCB of FIG. 16A.

The PCB 1610 includes both horizontally extending and verticallyoriented dipole antenna elements. In particular, the horizontallyoriented dipole antenna elements 1620 may include a first dipole arm1630 including a proximal section 1632 and a distal section 1634extending perpendicularly from the proximal section 1632 in a firstdirection parallel to the free end 1612 of the PCB 1610. Horizontallyextending dipole antenna element 1620 also includes a second arm 1640including a proximal section 1642 and a distal section 1644 extendingperpendicularly from the proximal section 1642 in a second directionopposite the first direction in which the distal section 1634 of thefirst dipole arm 1640 extends.

The proximal sections 1632 and 1642 of the first and second dipole arms1630 and 1640 of the horizontally oriented dipole antenna elements 1620may comprise parallel, overlapping striplines, and the distal sections1634 and 1644 may be parallel striplines which do not have substantialoverlap.

The vertically oriented dipole antenna elements 1670 may include anupper dipole arm 1680 including a proximal section 1682 and a distalsection 1684 extending perpendicularly from the proximal section 1632 inan upward, vertical direction. The distal section may be defined by orinclude a via extending between the proximal section 1682 and may extendto an upper surface of the PCB 1610. The via may be a cylindrical via,and may in some embodiments be a solid cylindrical via or a hollowcylindrical via.

The vertically oriented dipole antenna elements 1670 also include alower dipole arm 1690 including a proximal section 1692 and a distalsection 1694 extending perpendicularly from the proximal section 1692 inan downward, vertical direction. The distal section may be defined by orinclude a via extending between the proximal section 1692 and may extendto a lower surface of the PCB 1610.

The proximal sections 1682 and 1692 of the upper and lower dipole arms1680 and 1690 of the vertically oriented dipole antenna elements 1670may comprise parallel, overlapping striplines, and the upper and lowerdistal sections 1684 and 1694 may be axially aligned cylindrical vias oraxially aligned structures of another shape. The upper and lower distalsections 1684 and 1694 may in some embodiments be of unequal length, andthe space between the upper and lower distal sections 1684 and 1694 maynot be located at the exact midpoint between the upper and lowersurfaces of the PCB 1610.

As can best be seen in FIG. 16B, the proximal section 1632 and distalsection 1634 of the first horizontally oriented dipole antenna arm 1630may be generally coplanar with the proximal section 1682 of the uppervertically oriented dipole antenna arm 1680. These proximal sections1632 and 1682 may be connected to a ground plane (not shown), which mayin some embodiments be coplanar with each of the proximal sections 1632and 1682.

As can be seen in FIG. 16C, the proximal section 1642 of the secondhorizontally oriented dipole antenna arm 1640 and the proximal section1692 of the lower vertically oriented dipole antenna arm 1690 may beconnected to respective signal lines 1646 and 1696. In the illustratedembodiment, these signal lines 1646 and 1696 are coplanar with theproximal section 1642 of the second horizontally oriented dipole antennaarm 1640 and the proximal section 1692 of the lower vertically orienteddipole antenna arm 1690, although other configurations may also be used,as discussed in greater detail below.

As can be seen in FIG. 16D, the asymmetrical configuration of thesublayers of PCB 1610 illustrate that while the antenna elements may beintegrated within the PCB, these antenna elements are not necessarilylocated in the exact middle of the PCB, but may instead beasymmetrically positioned within the PCB 1610.

In addition to the ground layer to which the proximal section 1642 ofthe second horizontally oriented dipole antenna arm 1640 and theproximal section 1692 of the lower vertically oriented dipole antennaarm 1690, the PCB 1610 may also include at least a second ground planeon the opposite side of these striplines as the first ground plane. Eachof these ground planes, as well as any other horizontally extendingground planes, may be connected to the vertically extending vias 1608which form the vertical ground-plane-like structure. The inclusion ofthe vertically extending vias 1608 can, for example, improve thefront-to-back ratio of the antenna array.

FIG. 17 is a perspective view illustrating another embodiment of a PCBhaving a plurality of components supported on a first side thereof. Likethe PCB 1210 of FIG. 12, the PCB 1710 includes a distal portion 1760 atthe free end 1714 of the PCB 1710 which is thicker than a proximalportion 1770 closer to the fixed end 1712 at which the PCB 1710 will besupported by a backplane.

In addition to a plurality of alternating horizontally and verticallyoriented dipole antenna elements embedded within the thicker distalportion 1760 of the PCB 1710 near the free end of the PCB 1710, thethicker distal portion 1760 also supports a number of additionalcomponents. In particular, a pair of beamforming integrated circuits1762 a and 1762 b are located on the thicker distal portion 1760 of thePCB 1710.

Outward of the beamforming integrated circuits 1762 a and 1762 b andinward of the embedded dipole antenna elements near the free end 1714 ofthe PCB 1710 are a number of switches 1764, each of which iselectrically connected between an embedded dipole element and one of thebeamforming ICs 1762 a and 1762 b. These switches 1764 may be RFswitches and can be used, for example, to operate the antenna arrayusing time division duplexing.

Connections between the various components of the PCB may be made usinga combination of vias and printed traces or other conductive structures.Striplines within the PCB 1710 may be phase-matched to assist withbeamforming.

The PCB 1710 may also include spacers 1766 which can be used to maintaina desired spacing between adjacent PCBs to provide and maintain desireddimensions for the resulting antenna array. This connection usingspacers 1766 may be purely mechanical, and may provide precisearrangement of the dipole elements in the overall antenna array withoutthe need to also provide complex electrical connections from the PCB1710 to an antenna array substrate.

In addition to the components supported by the thicker distal portion1760 of the PCB 1710, the proximal portion 1770 also supports aplurality of components. In the illustrated embodiment, the proximalportion includes various components including connectors 1772 which canbe used to electrically connect components of PCB 1710 to a backplaneand other operational components of the antenna array supported to orconnected via the backplane. In addition, one or more thermaldissipation structures 1774 are disposed on the thinner proximal portion1770 of the PCB 1710.

The various components of the PCBs 1710, particularly the beamformingICs 1762 a and 1762 b, can generate substantial amounts of heat duringoperation. Because the antenna array will include a plurality of PCBs1710 in a parallel arrangement close to one another, and because theoverall spacing between the PCBs 1710 is a function of the desiredspacing between the antenna elements in adjacent PCBs 1710, the spacingbetween PCBs 1710 cannot be directly adjusted to increase thermaldissipation of this heat generated by the PCB components. However, byproviding a PCB 1710 with a thicker portion and a thinner portion,additional spacing may be provided to improve the thermal management ofthe antenna array.

The thicker portion of the PCB can be dimensioned to accommodate theheight of the vertically oriented dipole antenna element and anyadditional structures, and the thinner portion of the PCB 1710 canaccommodate the height of the thermal dissipation structure 1774. Thiscan allow the use of thermal dissipation structures 1774 having tallerfins or similar heat-dissipation structures, as well as provideclearance between the thermal dissipation structure 1774 and an adjacentPCB, improving airflow and convective heat transfer.

In addition, in the illustrated embodiment, most or all of thecomponents supported by the PCB are disposed on a single face of thePCB. In particular, the illustrated embodiment includes a singlegenerally planar face extending the length of the PCB which supports allof the PCB components which extend substantially outward from the faceof the PCB. The opposite side of the PCB includes two substantiallyplanar surfaces, one on the back of the thicker portion and one on theback of the thinner portion. These substantially planar surface can alsoimprove airflow along the PCB, improving conductive heat transfer awayfrom the PCB.

In the PCB illustrated in FIG. 16C, the striplines connecting the dipoleantenna elements to the signal are in the same plane as the printedcomponents of the dipole antenna elements. In other embodiments,however, such as the embodiment of FIG. 17 in which the beamforming ICsand switches are located on the upper surface of the PCB, at least aportion of the signal lines connecting the beamforming ICs and switchesto the embedded dipole antenna elements may be located at or near theupper surface of the PCB. Because the printed portions of the dipoleantenna elements are located near the vertical midpoint of the PCB, oneor more additional vias can be used to place the signal lines inelectrical communication with the embedded dipole antenna elements.

FIG. 18 is a top plan view schematically illustrating an alternativeembodiment of a via arrangement in which a portion of the signal linesare not coplanar with the printed dipole components of the embeddeddipole antenna elements. In particular, FIG. 18 schematicallyillustrates certain via placement for four adjacent dipole antennaelements, two horizontally oriented, and two vertically oriented. A via1888 can be used to provide a vertical connection with a proximalsection 1892 of a lower arm of a vertically-oriented embedded dipoleantenna element. The distal section 1894 of the lower arm of thevertically-oriented embedded dipole antenna element is placed incommunication with the signal line using the via 1888.

Similarly, a via 1848 can be used to provide a vertical connection witha proximal section 1842 of a second arm of a horizontally-orientedembedded dipole antenna element. The distal section 1844 of the secondarm of the horizontally-oriented embedded dipole antenna element isplaced in communication with the signal line using the via 1848.

In some embodiments, the portions of the vertically-oriented embeddeddipole antenna element and horizontally-oriented embedded dipole antennaelement connected to ground planes may be connected in-plane, while inother embodiments, additional vias may also be used in the formation ofthese connections.

The via arrangement also includes a plurality of vertically extendingvias 1808 surrounding each of the vias 1848 and 1888. These verticallyextending vias 1808 may serve the same purpose as the vias 1708 of thePCB 1710 of FIG. 17A, connecting ground planes and functioning as acontiguous orthogonal ground plane to improve the front-to-back ratio ofthe antenna array. As can be seen in FIG. 18, these vias 1808 need notbe aligned with one another, but can be located at various distancesfrom the end of the PCB.

FIG. 19 is a cross-sectional view schematically illustrating anembodiment of a layer stack which can be used to fabricate a PCB such asthe PCB 1710 of FIG. 17. The layer stack 1900 includes a top overlay1902 over a top solder layer 1906, and a bottom overlay 1904 over abottom solder layer 1908. Between these layers are conductive layers1911 through 1928, each of which is spaced apart from one another by atleast one of dielectric layers 1930 through 1948. Layers 1911 through1918, and the intervening layers form the thin portion of the PCB, alongwith top overlay 1902 and top solder layer 1906, while all of the layersare present in the thick portion of the PCB.

Layer 1911 may be a top conductive layer, and layers 1912 and 1914 maybe ground planes. Layer 1913 may be used for a combination of power andsignal. Layer 1915 may also be used to provide power. Layer 1918 may beused for a combination of power and ground. Layers 1916 and 1917 may beused to provide a combination of ground and signal.

In some embodiments, layers 1912 through 1917 may be formed first, andpatterned, drilled, etched, or otherwise modified to form through vias1952 and vias 1962 connecting structures within layer 1912 to structureswithin layer 1913.

Layers 1911 and 1918 may then be formed on respective sides of theexisting structure, and patterned, drilled, etched, or otherwisemodified to form through vias 1954 and vias 1964 connecting structureswithin layer 1911 to structures within layer 1912. In some embodiments,the through vias 1954 may form the grounded vertical sections ofembedded vertically oriented dipole antenna elements.

Layers 1919 through 1926 may be formed as a separate structure, andpatterned, drilled, etched, or otherwise modified to form through vias1972, which may form the signal-connected vertical sections of embeddedvertically oriented dipole antenna elements.

Then, the two structures may be brought together, and patterned,drilled, etched, or otherwise modified to form through vias 1974extending through all of the conductive layers and which may serve asthe vias which function as an orthogonal ground plane, as well asthrough vias 1976 which may form be used to connect signal lines to thesignal-connected portions of the embedded dipole antenna elements. Thismay include the use of a backdrill process.

In some embodiments, copper may be used as the conductive material,although in other embodiments, other suitable materials may also beused. Any suitable dielectric material may be used to form thedielectric layers, and the various dielectric layers may be formed fromdifferent dielectric materials in the same printed circuit board.

FIG. 20A is a top plan view of a PCB such as the PCB 1700 of FIG. 17,illustrating certain vias and conductive traces formed between variouscomponents. FIG. 20B is a bottom plan view of the PCB of FIG. 20A. Asdiscussed above, it can be seen in the illustrated embodiment that themajority of the components supported by the PCB are supported on the topsurface visible in FIG. 20A, and that the bottom generally planarsurfaces visible in FIG. 20B are generally devoid of any structuressupported thereon.

In the foregoing description, specific details are given to provide athorough understanding of the examples. However, it will be understoodby one of ordinary skill in the art that the examples may be practicedwithout these specific details. Certain embodiments that are describedseparately herein can be combined in a single embodiment, and thefeatures described with reference to a given embodiment also can beimplemented in multiple embodiments separately or in any suitablesubcombination. In some examples, certain structures and techniques maybe shown in greater detail than other structures or techniques tofurther explain the examples.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. An antenna array, comprising: a backplane; and aplurality of printed circuit boards supported at a first edge by thebackplane, the plurality of printed circuit boards arranged parallel toand spaced apart from one another, each of the plurality of printedcircuit boards including a linear array of dipole antenna elementsarranged along a second free edge of the printed circuit board oppositethe first edge of the printed circuit board, the linear array of dipoleantenna elements on each of the plurality of printed circuit boardscooperating with one another to form a two-dimensional array of printedcircuit boards; wherein each of the plurality of printed circuit boardsincludes a first portion proximate the backplane and having a firstthickness and a second portion proximate the second free edge of theprinted circuit board and having a second thickness greater than thefirst thickness; wherein each of the plurality of printed circuit boardsincludes a thermal dissipation structure supported by the first portionof the printed circuit board; and wherein the thermal dissipationstructure includes a plurality of fins.
 2. The antenna array of claim 1,wherein the plurality of printed circuit boards are arranged orthogonalto the backplane.
 3. The antenna array of claim 2, wherein each of thelinear array of dipole antenna elements comprises: a first dipole armthat comprises a proximal section that extends normal to the backplaneand a distal section that extends perpendicular from the proximalsection in a first direction that is parallel to the backplane; and asecond dipole arm that comprises a proximal section that extends normalto the backplane and a distal section that extends perpendicular fromthe proximal section in a second direction, that is opposite from thefirst direction, the second direction also being parallel to thebackplane.
 4. The antenna array of claim 1, wherein the linear array ofdipole antenna elements is at least partially embedded within the secondportion of the printed circuit board.
 5. The antenna array of claim 1,wherein the linear array of dipole antenna elements includes a firstsubset of dipole antenna elements oriented in a first direction and asecond subset of dipole antenna elements oriented in a second direction.6. The antenna array of claim 5, wherein the first subset of dipoleantenna elements are horizontally oriented and include a pair ofparallel, non-coplanar sections, and wherein the second subset of dipoleantenna elements are vertically oriented and include a pair of axiallyaligned vias spaced apart from one another.
 7. The antenna array ofclaim 5, wherein the dipole antenna elements of the first subset ofdipole antenna elements alternate with the dipole antenna elements ofthe second subset of dipole antenna elements along the length of thelinear array of dipole antenna elements.
 8. An antenna array,comprising: a backplane; and a plurality of printed circuit boardssupported at a first edge by the backplane, the plurality of printedcircuit boards arranged parallel to and spaced apart from one another,each of the plurality of printed circuit boards including a linear arrayof dipole antenna elements arranged along a second free edge of theprinted circuit board opposite the first edge of the printed circuitboard, the linear array of dipole antenna elements on each of theplurality of printed circuit boards cooperating with one another to forma two-dimensional array of printed circuit boards; wherein each of theplurality of printed circuit boards includes a first portion proximatethe backplane and having a first thickness and a second portionproximate the second free edge of the printed circuit board and having asecond thickness greater than the first thickness; and wherein thelinear array of dipole antenna elements is at least partially embeddedwithin the second portion of the printed circuit board.
 9. The antennaarray of claim 8, wherein the plurality of printed circuit boards arearranged orthogonal to the backplane.
 10. The antenna array of claim 9,wherein each of the linear array of dipole antenna elements comprises: afirst dipole arm that comprises a proximal section that extends normalto the backplane and a distal section that extends perpendicular fromthe proximal section in a first direction that is parallel to thebackplane; and a second dipole arm that comprises a proximal sectionthat extends normal to the backplane and a distal section that extendsperpendicular from the proximal section in a second direction, that isopposite from the first direction, the second direction also beingparallel to the backplane.
 11. The antenna array of claim 10, whereinthe proximal sections of the first and second dipole arms compriseparallel overlapping striplines.
 12. The antenna array of claim 11,wherein the distal sections of the first and second dipole arms areparallel with one another and extend in opposite directions and do nothave substantial overlap.
 13. The antenna array of claim 10, whereineach of the linear array of dipole antenna elements comprises areflector comprising a strip located outward of the first dipole arm andthe second dipole arm proximate the second free edge of the printedcircuit board.
 14. The antenna array of claim 8, wherein each of theplurality of printed circuit boards includes a thermal dissipationstructure supported by the first portion of the printed circuit board.15. The antenna array of claim 14, wherein the thermal dissipationstructure includes a plurality of fins.
 16. An antenna array,comprising: a backplane; and a plurality of printed circuit boardssupported at a first edge by the backplane, the plurality of printedcircuit boards arranged parallel to and spaced apart from one another,each of the plurality of printed circuit boards including a linear arrayof dipole antenna elements arranged along a second free edge of theprinted circuit board opposite the first edge of the printed circuitboard, the linear array of dipole antenna elements on each of theplurality of printed circuit boards cooperating with one another to forma two-dimensional array of printed circuit boards; wherein each of theplurality of printed circuit boards includes a first portion proximatethe backplane and having a first thickness and a second portionproximate the second free edge of the printed circuit board and having asecond thickness greater than the first thickness; wherein the lineararray of dipole antenna elements includes a first subset of dipoleantenna elements oriented in a first direction and a second subset ofdipole antenna elements oriented in a second direction; and wherein thefirst subset of dipole antenna elements are horizontally oriented andinclude a pair of parallel, non-coplanar sections, and wherein thesecond subset of dipole antenna elements are vertically oriented andinclude a pair of axially aligned vias spaced apart from one another.17. The antenna array of claim 16, wherein the dipole antenna elementsof the first subset of dipole antenna elements alternate with the dipoleantenna elements of the second subset of dipole antenna elements alongthe length of the linear array of dipole antenna elements.
 18. Theantenna array of claim 16, wherein each of the plurality of printedcircuit boards includes a thermal dissipation structure supported by thefirst portion of the printed circuit board.
 19. The antenna array ofclaim 18, wherein the thermal dissipation structure includes a pluralityof fins.
 20. The antenna array of claim 19, wherein the plurality ofprinted circuit boards are arranged orthogonal to the backplane.